This invention relates to a method for the treatment of a metal substrate for the growth of a hydrogen-containing semiconductor film.
Amorphous silicon possesses a great ability to absorb light and a consequent outstanding photoconductive property. Owing to these excellent properties, amorphous silicon is expected to find utility in applications to solar batteries, photoelectric conversion elements, etc. Among the methods heretofore proposed for the manufacture of amorphous silicon, there are included a glow discharge method which comprises exposing a molecular gas such as silane (SiH.sub.4) with a reduced pressure to glow discharge inside a reactor thereby decomposing the silane and causing the produced silicon to be deposited on a metal substrate placed inside the reactor and a reactive sputtering method which comprises sputtering solid silicone out in an atmosphere containing hydrogen and causing the sputtered silicon to be deposited on a metal substrate. In preparation for the growth of a hydrogen-containing silicon composite on a metal substrate as described above, the surface of the metal substrate is cleansed with an organic solvent or subjected to a chemical etching treatment using an aqueous solution. The electric contact property between the formed silicon film and the metal substrate, however, cannot be obtained with high repeatability. This lack of repeatability of the electric contact property has posed itself a problem in the fabrication of devices using amorphous silicon. For example, it has been difficult to afford required control of the properties of barrier height and barrier width between the film of amorphous silicon and the metal substrate and it has been infeasible to establish an ohmic contact between the semiconductor and the metal substrate with high uniformity or high repeatability when the semiconductor containing p-type or n-type impurities excessively.
Recently, there has been proposed a method in which, in the same vacuum system, a metal substrate is formed and, subsequently, a film of amorphous silicon is continuously deposited on the metal substrate. This method entails a technically complicated procedure and fails to provide the contact property with high repeatability.